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Thread: 1978 atc 90

  1. #1
    Join Date
    Sep 2021
    Location
    San Antonio tx
    --
    4

    1978 atc 90

    Need help

    78 atc 90 has spark and new carburetor but it wont start. Check points and they seem to be in good shape what am i missing???

  2. #2
    Join Date
    Jul 2009
    Location
    South Florida
    --
    6,430
    Check compression
    78 atc 90/180cc Dickson Full Suspension
    76 ATC90/180cc Nicholson
    77 atc 90 Dickson Full Suspension
    84 KLT 110/123cc Powroll Racer from 80s
    87 atc 125m stock
    84 atc 200x Curtis Sparks
    84 atc 200x Powroll My race bike from 80's
    83 atc70/108cc Powroll blue Xmas Special
    81 atc185s HP-ATC full suspension

    Performance Shop is Open PM me for Service

    My Feedback http://www.3wheelerworld.com/showthr...ck+shortline10

  3. #3
    Join Date
    Sep 2021
    Location
    San Antonio tx
    --
    4

    What should compression be?

    Quote Originally Posted by shortline10 View Post
    Check compression
    What should compression be

  4. #4
    Join Date
    Jul 2009
    Location
    South Florida
    --
    6,430
    Should be anywhere from 150-190 but as long as your 100+ it should run .
    78 atc 90/180cc Dickson Full Suspension
    76 ATC90/180cc Nicholson
    77 atc 90 Dickson Full Suspension
    84 KLT 110/123cc Powroll Racer from 80s
    87 atc 125m stock
    84 atc 200x Curtis Sparks
    84 atc 200x Powroll My race bike from 80's
    83 atc70/108cc Powroll blue Xmas Special
    81 atc185s HP-ATC full suspension

    Performance Shop is Open PM me for Service

    My Feedback http://www.3wheelerworld.com/showthr...ck+shortline10

  5. #5
    Join Date
    Sep 2021
    Location
    San Antonio tx
    --
    4
    Compression was 45lbs so definitely needs a rebuild. Who sells a top end kit

  6. #6
    Join Date
    Nov 2015
    Location
    Davenport iowa
    --
    1,111
    Quote Originally Posted by Alfredo3 View Post
    Compression was 45lbs so definitely needs a rebuild. Who sells a top end kit
    You can find a piston and rings on either this site or eBay. You’ll need to decide if you want to go hi Performnce with the piston or just a basic over bore. Going big ( high compression) will sip into the pocket book a bit because you will then want a performance cam, bigger carb and ported head. Decide what route you want to go and then start pricing your options
    90 nickolson Bored and Stroked "The Good"

    Big Bore 110 Pauter frame "The Bad"

    90 Bored and Stroked “vey’s frame” "The Ugly"

    110 JSC frame Bored and Stroked
    flat track build. “Shop trike”

    1974 original 90 X 2

    1974 Original 70.

  7. #7
    Join Date
    Apr 2014
    Location
    Edmond, KS
    --
    2,236
    Quote Originally Posted by Alfredo3 View Post
    Compression was 45lbs so definitely needs a rebuild. Who sells a top end kit
    Before you dive into the top end, check your valve clearances to make sure that the valves are closing all the way.

  8. #8
    Join Date
    Sep 2021
    Location
    San Antonio tx
    --
    4

  9. #9
    Join Date
    Jul 2009
    Location
    South Florida
    --
    6,430
    No that kit won’t work . A trx90 is a completely different motor .


    Quote Originally Posted by Alfredo3 View Post
    78 atc 90/180cc Dickson Full Suspension
    76 ATC90/180cc Nicholson
    77 atc 90 Dickson Full Suspension
    84 KLT 110/123cc Powroll Racer from 80s
    87 atc 125m stock
    84 atc 200x Curtis Sparks
    84 atc 200x Powroll My race bike from 80's
    83 atc70/108cc Powroll blue Xmas Special
    81 atc185s HP-ATC full suspension

    Performance Shop is Open PM me for Service

    My Feedback http://www.3wheelerworld.com/showthr...ck+shortline10

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